The invention relates to a method for marking or drilling holes in spectacle lenses, and to a device for carrying out the method.
The nose bridge and the bows of rimless spectacles are usually screwed onto the form-ground spectacle lenses. It is therefore necessary for the bores for fastening the nose bridge and the bows to be made in a positionally accurate fashion in the form-ground spectacle lenses. The position of these bores is determined by the shape of the spectacle lenses and of the nose bridge and the bows and fixed by the manufacturer of these parts. For the purpose of selecting such rimless spectacles, the elements, screwed onto a so-called support disk, are supplied and permit the rimless spectacles to be tried without the use of optical lenses. Frequently, a pattern disk for grinding the contour of the spectacle lenses is also supplied with the rimless spectacles, and this pattern disk is likewise provided by the manufacturer with the bores for fastening the spectacle frame elements.
The optician uses the pattern disk or support disk provided with the fastening bores to mark the bores on a spectacle lens, and drills the holes by means of a suitable drilling device.
If the spectacle lenses are to be exchanged while retaining the elements of the spectacle frame, because, for example, the visual acuity of the spectacle wearer has changed, or because one of the spectacle lenses has been broken, it is possible to use an existing spectacle lens, already provided with bores, for marking the bores.
It is obvious that this marking of the bores and the subsequent drilling of the holes are attended by a substantial manual outlay which requires great skill on the part of the optician and therefore gives rise to costs which can also rise by virtue of the fact that drilling the holes by means of conventional drilling devices frequently leads to breakage of the spectacle lens, which can then no longer be used.
It is the object of the invention to simplify and speed up the marking or drilling of holes in spectacle lenses, to increase the accuracy and to reduce the risk of lens breakage when drilling.
Starting from this formulation of the problem, a method is proposed for marking or drilling holes in spectacle lenses, in which, according to the invention, the position of bores in a spectacle lens or a pattern disk or a support disk is scanned with or without contact, the data acquired on the position of the bores are fed to a computer as rectangular or polar coordinates and used to control the marking or drilling by means of a CNC-controlled marking or drilling device.
The invention proceeds from the consideration that the outlay on acquiring the data on the position of the bores is small, since only one pair of values (x, y), (r, xcfx86) is required for each bore, and these pairs of values can accurately and quickly effect control of the marking or the drilling by means of a CNC-controlled marking or drilling device.
The marking of the holes can be performed by means of an ink jet or a counterboring cutter. In this case, the actual drilling of the holes is carried out in a conventional drilling device.
The holes are preferably drilled by means of a CNC-controlled drilling device, it being necessary to adapt the drilling tool to the spectacle lens material. If, for example, silicate lenses are involved, it is preferred to use a diamond drilling tool, while drilling tools made from hard metal are suitable for drilling plastic lenses.
The scanning of the position of the bores can be carried out, for example, in a centering device for coquilles. Such centering devices serve the purpose of mounting a holding element in the form of a block or sucker on a coquille which can be detected in a viewing optics or on a screen, and on which an image of the form-ground spectacle lens is superimposed in accordance with the spectacle frame, in order to insert the coquille in a positionally accurate fashion into a spectacle lens holding shaft on a spectacle lens edging machine, after which form grinding is carried out in accordance with the prescribed spectacle lens shape.
The scanning of the position of the bores can also be carried out in a device for scanning the contour of a pattern disk. By means of such a device, the contour of a pattern disk is acquired in the form of a data record and used to control the form grinding by means of a CNC-controlled spectacle lens edging machine. Moreover, it is also possible for the position of the bores to be scanned in a device for cutting support disks for spectacle frames. Support disks are used, inter alia, for the purpose of marking the viewing points of the spectacle wearer during adaptation to the new spectacle frame. Such a device for cutting support disks is described in DE 40 03 001 C1 of the same applicant.
A further possibility for scanning the position of the bores consists in making use for this purpose of a spectacle lens edging machine in which the marking or drilling of the holes is also performed. It is advantageous in this case to make use of the same computer for acquiring the data and for controlling the marking or drilling, as well as for controlling the form grinding of the spectacle lens.
A video system with screen display of the contour of the spectacle lens or the pattern disk or the support disk and the bores can also be used for scanning the position of the bores if this video system is set up such that the acquisition of the data on the position of the bores is performed by means of automatic image evaluation.
In the case of a video system without automatic image evaluation, or if the spectacle lens, the pattern disk or the support disk are laid onto a digitizing tablet, the data on the position of the bores can be acquired by marking the bores, which are visible on the screen or the digitizing tablet, by means of a cursor which can be moved by a keyboard or a computer mouse, and are recorded by clicking on the respective bore.
The position of the holes in spectacle lenses can be input in a particularly simple way as a data record into a computer which is used for directly controlling the marking or drilling by means of a CNC-controlled marking or drilling device. This inputting of the data record can be accomplished in the form of rectangular or polar coordinates by means of a keyboard connected to the computer, or by reading in the data record, which is stored on a floppy disk, an EPROM or a magnetic strip, or is represented by means of a barcode. These stored data records can be supplied by the manufacturer of the spectacle frame, and can also comprise a data record for grinding the circumferential contour of the spectacle lens. It is likewise possible to acquire these data records by scanning a spectacle lens, a pattern disk or a support disk.
In order to solve the problem mentioned at the beginning, there is proposed a marking or drilling device for marking or drilling holes in spectacle lenses, having an input device for inputting the coordinates (Xn, Y1; X2, Y2) or (rn, xcfx86n) of the holes into a computer and a positioning device, controlled by the computer in accordance with the input coordinates, for the marking or drilling device with reference to the spectacle lens. A laser drill may be used as the marking or drilling device.
If use is made of a drilling tool running at high speed, it is possible to use for this a drive designed as an air turbine, as a combined air-water turbine or as a high-frequency electric motor.
Particularly preferred is a marking or drilling device on a spectacle lens edging machine, having a computer for controlling the form grinding of spectacle lenses, at least one grinding wheel in a grinding chamber, a spectacle lens holding shaft which can rotate in a fashion capable of angle encoding, can be adjusted radially and axially relative to the grinding wheel and can be locked, an angle sensor for acquiring the angle of rotation (xcfx86n) of the spectacle lens holding shaft, a position sensor for acquiring the radial distance (Xn) of the spectacle lens holding shaft from the grinding wheel, a position sensor for acquiring the axial position (Zn) of the spectacle lens holding shaft with reference to the grinding wheel, and an input device for inputting coordinates (X1, Y1; X2, Y2) of the holes into the computer.
By virtue of the fact that the marking or drilling device is arranged on the spectacle lens edging machine, it can be controlled by the same computer which is also used to control the form grinding of spectacle lenses.
The marking or drilling device can be arranged such that it can be telescoped in the X-direction either in a niche of the grinding chamber or outside the grinding chamber, in the first case the spectacle lens to be marked or drilled being held at that point in the spectacle lens holding shaft at which the form grinding is also carried out while, in the second case, a holder is to be provided for a spectacle lens, which is to be marked or drilled, outside the grinding chamber on the spectacle lens holding shaft.
When the marking or drilling device is coupled in terms of movement to the spectacle lens holding shaft or the grinding wheel in the X-direction and Z-direction, the positioning of the marking or drilling device with reference to the spectacle lens held by the spectacle lens holding shaft can be performed by the computer in a fashion controlled as a function of the input coordinates of the holes, the same movement control being used for this purpose as also serves for the form grinding of the spectacle lens.
It is also advantageously possible to arrange the scanning device for the position of the bores in a spectacle lens or a pattern disk or a support disk on the spectacle lens edging machine, and to couple it in terms of movement to the spectacle lens holding shaft or the grinding wheel in the X-direction and Z-direction. In this case, a sensing arm can project radially into the region of the spectacle lens held by the spectacle lens holding shaft, of the pattern disk or the support disk, a sensing element which acts with or without contact being arranged on the sensing arm.
When the sensing element is designed as a sensing pin, this sensing pin can guided in the X-direction and Z-direction up to the respective bore in the spectacle lens or the pattern disk or support disk, which is brought into the region of the sensing element by rotating the spectacle lens holding shaft. The coordinates of the hole are recorded in this case and fed to the computer.
The sensing element can also be designed as an optoelectronic sensing device which is capable of recording the coordinates of a hole in a spectacle lens held by the spectacle lens holding shaft, a pattern disk or a support disk.
A linear, optoelectronic sensing device, for example a charge-coupled (CCD), linear image scanner can preferably be arranged on the sensing arm which, during a revolution of the spectacle lens holding shaft detects both the position of the bores and the circumferential contour of a spectacle lens, of a pattern disk or a support disk, and feeds them to the computer for controlling the form grinding and the marking and drilling of the holes.
The scanning device can be arranged both inside and outside the grinding chamber and serves simultaneously as a marking or drilling device when, for example, the sensing pin is simultaneously the drilling tool, or when the optoelectronic sensing device is designed as a laser device which, by controlling the intensity of the laser beam, can be used both as a scanning device and as a marking or drilling device.